|  |  | Summary

Now that you completed this chapter, you should have a firm understanding of the following: ACLs perform several functions within a Cisco router, including implementing security/access procedures. ACLs are used to control and manage traffic. For some protocols, you can apply up to two ACLs to an interface: one inbound ACL and one outbound ACL. With ACLs, after a packet is matched with an ACL statement, it can be denied or permitted the use of the associated interface. Wildcard mask bits use the number one and the number zero to identify how to treat the corresponding IP address bits. The two main types of ACLs are standard ACLs and extended ACLs. ACLs can be configured for all routed network protocols to filter those protocols' packets as the packets pass through a router. ACLs are typically used in firewall routers, which are often positioned between the internal network and an external network such as the Internet.
| Threaded Case Study
| Washington School District Project Task: Using ACLs In this chapter, you have learned concepts and configuration processes that will help you implement ACLs. In the previous chapters we learned the concepts of how data traffic flows across a LAN; in this chapter we will study the methods for controlling the flow of these data packets based on layer 2&3 addressing and layer 4 services. The TCS Overview dictates that each school will have two networks, one for curriculum and the other for administration. Each unique LAN segment is connected to a separate Ethernet port on the router. You should devise an ACL for the router that will deny anyone from the curriculum LAN access into the Administrative LAN segment, yet continue to give the Administrative LAN complete access into the Curriculum LAN segment. One exception to this ACL is the router is to pass any DNS or e-mail packets to the DNS/Email server which is located on the Administration LAN segment. In response to the network design and security requirements, you need to complete the following tasks: Document why you would need ACLs and create a logical diagram describing the overall effect of these ACLs on the entire district network. Document what type of ACL will be placed on the high-end, powerful, district core router(s), and where they will be placed and why. Document the router command sequence required to implement each ACL on each of the local school site access router's interfaces and document the resulting changes to the router configuration. Document the effect of each ACL as it relates to traffic flow across individual school LANs and the overall district network. Continue LAN Design Tasks: Site Wiring Designs, LAN Logical Designs, Typical MDF and IDF Designs and Electronics Tables, and a Site-specific LAN Electronics List Apply the CCNA Certification Exam Learning Objectives to your specific design. This will require a paragraph on how the learning objectives relate to your design. Learning objectives can be grouped together for the purpose of explanation. In this way, you will be studying for their CCNA Certification Exam as you work through the case study. CCNA Certification Exam Learning Objectives (*** are explicit CCNA Exam objectives; unmarked are knowledge assumed by the exam): General Describe what an access control list is. Describe the function of Access control lists on routers. Describe the reasons access control list are used. Describe how segmentation with routers and access control lists are related. Configure Standard and extended access lists to filter IP traffic.*** Monitor and verify selected access list operations on the router.*** OSI model Define what layers of the OSI model standard access control lists function at and what fields in the data packet header it is concerned with. Define what layers of the OSI model extended access control lists function at and what fields in the data packet header it is concerned with.
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